Given the following schema for a customer relation:

Customer$-$schema $=($cust$\_$id$,$ first$\_$name, last$\_$name, salesperson$\_$id$,$ email, store$\_$id$)$

Where:

cust$\_$id is the customer$$s id

first$\_$name is the customer$$s first name

last$\_$name is the customer$$s last name

salesperson$\_$id is the unique id of the salesperson assigned to the customer

email is the customer$$s email address

store$\_$id is the id of the of the store closest to the customer

List all of the possible candidate keys for the customer$-$schema when ALL OF the following constraints are

imposed. Note that since all of the constraints must hold, you should produce only one list.

a$.$ Each customer will be represented by exactly one tuple

b$.$ Each customer has a unique id

c$.$ No two customers will have the same email address

d$.$ A salesperson will not be assigned two customers with the same name

e$.$ A salesperson will be based out of a store and all of the salesperson$$s customers will have the

same store$\_$id

f$.$ A store can have any number of cutomers